How do I partially update an object in MongoDB so the new object will overlay merge with the existing one

Question

Given this document saved in MongoDB         id           some key             param1    val1           param2    val2           param3    val3           An object with new information on param2 and param3 from the outside world needs to be saved  var new info         param2    val2 new       param3    val3 new       I want to merge   overlay the new fields over the existing state of the object so that param1 doesn t get removed  Doing this  db collection update      id           set    some key   new info         Will lead to MongoDB is doing exactly as it was asked  and sets some key to that value  replacing the old one         id           some key           param2    val2 new         param3    val3 new           What is the way to have MongoDB update only new fields  without stating them one by one explicitly   to get this         id           some key             param1    val1           param2    val2 new           param3    val3 new           I m using the Java client  but any example will be appreciated

User · Answer

use  set do this process   update    id   args dashboardId   viewData  id   widgetId     set    viewData   widgetData   widgetDoc widgetData     exec    then dashboardDoc   gt        return           result  dashboardDoc

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Make an update object with the property names including the necessary dot path     somekey    from OP s example   and then use that do the update     the modification that s requested updateReq         param2    val2 new      param3    val3 new          build a renamed version of the update request var update       for var field in updateReq       update  somekey   field    updateReq field        apply the update without modifying fields not originally in the update db collection update    id        set update   upsert true  function err result

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Yeah  the best way is to convert the object notation to a flat key-value string representation  as mentioned in this comment  https   stackoverflow com a 39357531 2529199  I wanted to highlight an alternative method using this NPM library  https   www npmjs com package dot-object which lets you manipulate different objects using dot notation   I used this pattern to programatically create a nested object property when accepting the key-value as a function variable  as follows   const dot   require  dot-object     function docid  varname  varvalue     let doc   dot dot          varname   varvalue           Mongo update   id docid    set doc        This pattern lets me use nested as well as single-level properties interchangeably  and insert them cleanly into Mongo   If you need to play around with JS Objects beyond just Mongo  especially on the client-side but have consistency when working with Mongo  this library gives you more options than the earlier mentioned mongo-dot-notation NPM module   P S I originally wanted to just mention this as a comment but apparently my S O rep isn t high enough to post a comment  So  not trying to muscle in on SzybkiSasza s comment  just wanted to highlight providing an alternative module

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I tried findAndModify   to update a particular field in a pre-existing object   https   docs mongodb com manual reference method db collection findAndModify

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If I understand the question correctly  you want to update a document with the contents of another document  but only the fields that are not already present  and completely ignore the fields that are already set  even if to another value    There is no way to do that in a single command   You have to query the document first  figure out what you want to  set and then update it  using the old values as a matching filter to make sure you don t get concurrent updates in between      Another reading of your question would be that you are happy with  set  but do not want to explicitly set all fields  How would you pass in the data then   You know you can do the following   db collection update      id           set  someObjectWithNewData

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I had success doing it this way   db collection update      id           set     key another key    new info           I have a function that handles my profile updates dynamically  function update prop  newVal      const str    profile   prop      db collection update     id          set     str   newVal            Note   profile  is specific to my implementation  it is just the string of the key that you would like to modify

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Mongo lets you update nested documents using a   convention  Take a look  Updating nested documents in mongodb  Here s another question from the past about a merge update  like the one you re looking for I believe  MongoDB atomic update via   39 merge  39  document

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where clause DBObject     DBObject query   new BasicDBObject   id   new ObjectId id            modifications to be applied     DBObject update   new BasicDBObject            set new values     update put   set   new BasicDBObject  param2   value2            update the document     collection update query  update  true  false     3rd param- gt upsertFlag  4th param- gt updateMultiFlag   If you have multiple fields to be updated          Document doc   new Document            doc put  param2   value2            doc put  param3   value3            update put   set   doc

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I solved it with my own function  If you want to update specified field in document you need to address it clearly   Example          id            some key             param1    val1           param2    val2           param3    val3            If you want to update param2 only  it s wrong to do   db collection update      id           set    some key   new info         WRONG   You must use   db collection update      id           set    some key param2   new info           So i wrote a function something like that   function  update  id   data   options array           temp   array        foreach  data as  key   gt   value                 temp  some key    key     value               collection- gt update          array   id    gt   id           array   set    gt   temp              update  1   array  param2    gt   some data

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It looks like you can set isPartialObject which might accomplish what you want

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You have to use Embedded Documents  stringfy the path object   let update      Object getOwnPropertyNames new info  forEach param   gt       update  some key     param    new info param       And so  in JavaScript you can use Spread Operator       to update  db collection update      id           set       update

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You can use dot-notation to access and set fields deep inside objects  without affecting the other properties of those objects   Given the object you specified above    gt  db test insert   id    test object    some key     param1    val1    param2    val2    param3    val3     WriteResult    nInserted    1      We can update just some key param2 and some key param3    gt  db test findAndModify       query    id    test object        update     set     some key param2    val2 new    some key param3    val3 new         new  true                id    ObjectId  56476e04e5f19d86ece5b81d         id     test object        some key               param1     val1            param2     val2 new            param3     val3 new            You can delve as deep as you like  This is also useful for adding new properties to an object without affecting the existing ones

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Starting Mongo 4 2  db collection update   can accept an aggregation pipeline  which allows using aggregation operators such as  addFields  which outputs all existing fields from the input documents and newly added fields   var new info     param2   val2 new   param3   val3 new          some key    param1   val1   param2   val2   param3   val3           some key    param1   val1   param2   val2                      db collection update         addFields    some key  new info         multi  true         some key    param1   val1   param2   val2 new   param3   val3 new           some key    param1   val1   param2   val2 new   param3   val3 new         The first part    is the match query  filtering which documents to update  in this case all documents   The second part     addFields    some key  new info      is the update aggregation pipeline    Note the squared brackets signifying the use of an aggregation pipeline  Since this is an aggregation pipeline  we can use  addFields   addFields performs exactly what you need  updating the object so that the new object will overlay   merge with the existing one  In this case    param2   val2 new   param3   val3 new    will be merged into the existing some key by keeping param1 untouched and either add or replace both param2 and param3   Don t forget   multi  true    otherwise only the first matching document will be updated

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You could rather do a upsert  this operation in MongoDB is utilized to save document into collection  If document matches query criteria then it will perform update operation otherwise it will insert a new document into collection   something similar as below   db employees update       type  FT          set  salary 200000         upsert   true

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You can use  mergeObjects in the aggregation based update  Something like db collection update        id             quot  set quot           quot some key quot             quot  mergeObjects quot               quot  some key quot             new info or   param2    quot val2 new quot   param3    quot val3 new quot                              More examples here

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db collection update      id           set    some key   new info         to  db collection update     id           set    some key    param1  newValue            Hope this help

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The best solution is to extract properties from object and make them flat dot-notation key-value pairs  You could use for example this library    https   www npmjs com package mongo-dot-notation  It has  flatten function that allows you to change object into flat set of properties that could be then given to  set modifier  without worries that any property of your existing DB object will be deleted overwritten without need   Taken from mongo-dot-notation docs   var person       firstName   John     lastName   Doe     address        city   NY       street   Eighth Avenu       number  123           var instructions   dot flatten person  console log instructions            set         firstName    John        lastName    Doe        address city    NY        address street    Eighth Avenu        address number   123            And then it forms perfect selector - it will update ONLY given properties  EDIT  I like to be archeologist some times

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You should think about updating the object interchangeably and then simply store the object with the updated fields  Something like done below  function update  id        return new Promise  resolve  reject    gt             ObjModel findOne   id   exec  err  obj    gt                 if err  return reject err               obj   updateObject obj                     some key                        param2    val2 new                       param3    val3 new                                                obj save  err  obj    gt                    if err  return reject err                  resolve obj                                       function updateObject obj  data         let keys   Object keys data       keys forEach key   gt             if  obj key   obj key    data key           if typeof data key      object                obj key    updateObject obj key   data key           else             obj key    data key              return obj

[mongodb] How do I partially update an object in MongoDB so the new object will overlay / merge with the existing one

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